Method for the production of a furniture body

ABSTRACT

In a method to produce a furniture body, a V-shaped groove is cut into a board of wood or similar material that includes a veneer on its outer surface from its inner side along each of several straight lines in the area of the body corner edge to be formed to a depth meeting the veneer. Subsequently, the body sides separated from each other are pivoted together by closing the V-shaped groove that forms the miter faces on which adhesive was placed, whereby the veneer layer is deformed or broken along the edge that is formed. For the purpose of producing a pivoting hinge, a smaller starter groove is cut to a depth up to the veneer layer at each location before the V-shaped groove is produced. This smaller starter groove possesses a groove base with a final width that extends to both sides over the face area of the V-shaped groove to be produced subsequently. A fluid adhesive is injected into the starter groove where it hardens, filling the starter groove at least partially from the veneer layer and binding with the material of the board and of the veneer layer. Subsequently, each V-shaped groove is cut through the board material and through the hardened plastic material so that an elastic, film-like spar of the plastic material remains between the face area of the V-shaped groove and the veneer layer.

TECHNICAL REALM

The invention relates to a method to produce a furniture body with body sides of wood or similar material that are bound together along common edges at miter faces. In this method, a V-shaped groove is cut into a board of wood or similar material that includes a veneer on its outer surface from its inner side along each of several straight lines in the area of the body corner edge to be formed to a depth meeting the veneer. Subsequently, the body sides separated from each other are pivoted together by closing the V-shaped groove that forms the miter faces on which adhesive was placed, whereby the veneer layer is deformed or broken along the edge that is formed.

STATE OF THE ART

Such a method is known from publication DE 31 09 965 A1. In this known method, an elastic adhesive that is sprayed onto the flanks of the so-called miter groove before the sides are swiveled together is inserted into the V-shaped groove. This adhesive has the task of holding the body sides together during the swivel or folding maneuver without having to adhere additional reinforcement strips on the side opposite the miter groove of the board forming the body sides. The problem here is that the elastic adhesive is supposed to form a film on the surfaces of the miter groove that remains within the miter joint resulting from folding the body sides. If the elastic adhesive is applied thinly to maintain a perfect fit of the miter faces, the film hinge formed by the adhesive does not possess adequate strength, depending on the thickness and weight of the body sides. If one therefore selects a thicker film layer, then the miter faces do not match perfectly, possibly resulting in a split in the area of the miter joint. The elastic adhesive also covers a considerable portion of the surfaces of the miter groove formed from the board material, and blocks this surface from binding with the assembly adhesive that is also required to be inserted into the V-shaped miter groove in order to provide a permanent, strong bond of the body sides in the area of the miter joints.

A method to produce another type of furniture body is known from patent document DE 198 49 504 C1. According to it, a groove is cut through the veneer layer of the finished side near each fold line of the initial board before cutting the V-shaped groove that is filled with a hardening plastic material. For this, injection channels must be drilled in the board from the side of the opposing board that drain into the groove cut from the outer side of the initial board. After the plastic material hardens, the V-shaped groove is so cut into the opposing board side that the face area of this V-shaped groove lies within the plastic material positioned on the outer side of the board. This plastic material in its hardened state is adequately elastic to form a film hinge by means of which the opposing body sides to be swiveled together during the folding process are held together. The difficulty with this method is sealing the groove along its entire length when injecting the plastic material into the groove on the outer side of the initial board in order to be able to completely fill the entire groove from the groove base to outer side of the veneer layer with the plastic material. The plastic material lying along the outer edges of the miter joints is clearly visible, which is seen as distracting in many cases on esthetic grounds.

THE INVENTION

It is the task of the invention to produce a method of the type indicated at the outset in which plastic material forming the film hinge is applied in such a manner that, when the body sides are folded, an exact match of the miter faces is not hindered, and because of which the board forming the veneer layer on the outer sides of the body sides is stabilized by the plastic material.

This task is solved by the invention by means of a method of the type described at the outset in that a starter groove smaller in cross-section is cut through to the veneer layer at each location for the purpose of creating a swiveling hinge before creation of the V-shaped groove. This starter groove possesses a groove base in the veneer layer with a final width that extends to both sides over the face area of the V-shaped groove to be subsequently created. A fluid plastic material that will harden in the starter groove is injected into it that fills from the veneer layer up to at least a partial height, and it binds with the material of the board and with the veneer layer. Each V-shaped groove is then so cut through the board material and the hardened plastic material that an elastic, film-type ring of the plastic material remains between the face area of the V-shaped groove and the veneer layer.

It is essential to the invention that the elastic plastic material forming the film hinge itself forms a portion of the groove flank as a miter face near the V-shaped groove, the miter groove. A larger volume of the fluid plastic material may be provided in the area of the groove base of the starter groove, which promotes a more intensive bond to the material of the initial board from which the body sides are separated from each other. This particularly applies during use of laminated plywood material, which possesses relatively great porosity, as the material for the initial board. When the starter groove is filled, the fluid plastic flows into the laminated plywood material and permeates it, resulting in a particularly high degree of adhesive strength. After each V-shaped groove is cut through the hardened plastic material, a sufficiently-sized contact area of the plastic material remains within the board material whose height is greater relative to the depth dimension of the V-shaped groove than the thickness of the film-type spar remaining in the face area of the V-shaped groove. The total film hinge is not formed merely by the elastic, film-type spar of plastic material in the face area of the V-shaped groove, but rather also from plastic spars of larger cross-section formed on both sides as one piece with this spar. These larger spars provide not only for secure seal of the entire hinge to the material of the initial board, but rather also stabilize the deformed or broken veneer layer during the folding process of the body sides, because the plastic material binds or adheres firmly also with the veneer layer. It is thus not the material of the initial board that protects the veneer layer from both sides of the fold line, but rather the hardened plastic material. Since the miter groove is cut into the plastic material in advance, those portions of the miter faces formed by the plastic material may be exactly sized, and an exact superimposition of the miter faces is not prevented during folding of the body sides.

Basically, the first cut into the initial board at the pertinent location may possess a wide variety of cross-sectional areas as long as it does not extend over the cross-section of the miter groove to be cut subsequently with the exception of the groove base at which the starter groove is wider than the miter groove in the face area. The starter groove intentionally possesses a rectangular cross-section, and is cut perpendicular to the board plane from the outer side of the initial board, which may be performed using a standard router, or in particular, a saw blade. With respect to the V-shaped groove or miter groove to be subsequently cut, the starter groove extends in mirror symmetry to the plane of symmetry. It is assumed that the V-shaped groove may only be made along a straight direction, which also applies to the pertinent starter groove.

As mentioned above, a preferred material for the initial board is a laminated plywood material that allows for good adhesion of the plastic material forming the film hinge because of its porosity. This film hinge is formed first by the film-type spar of plastic material, and second by the relatively larger hinge bands, which is how the plastic spars formed on both sides of the film-type spar are to be viewed that first are adjacent to the veneer layer and the board material and adhere firmly to them, and second, form the flanks of the V-shaped groove in its face area. In order to achieve a tighter bond especially with the plastic material in the area of the aforementioned spar, the fluid plastic material may also be injected into the starter groove under pressure. This depends on the viscosity of the plastic material in a fluid state. A polyurethane plastic with thermoplastic properties is particularly suited for this because this plastic is adequately fluid in a fluid state, and is particularly tough.

It may be advantageous for the tolerance differential to cut the V-shaped groove into the board with a flat bottom in the face area. The width of this flat bottom is less here than the width of the starter groove whose flanks are completely cut away during cutting of the V-shaped groove. Thus sufficient plastic material remains to both sides of the flat bottom to form the aforementioned attachment spars. Depending on the type of the veneer layer present on the outer surface of the initial board, it may be useful to etch or cut through the veneer layer on the side opposite the V-shaped groove. This depends on whether and how much the veneer layer may stretch, and accordingly, cracked edges along the fold line may be partially or completely prevented by the elasticity of the veneer layer. For harder materials for which cracked edges cannot be avoided, a smoothing step may follow by cutting or grinding a chamfer along the edges of the finished body. For this, the veneer layer may be ground down along a diagonal direction to the pertinent body edge to the plastic material lying under it and stabilizing the veneer layer. The veneer layer may basically also be removed in the edge area to the extent that the plastic material becomes visible at the suitably flattened body edge, which may be used esthetically, among other things.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

The invention will be described below in greater detail using illustrations of an embodiment example, which show:

FIG. 1 A side view of a section of a board used to form opposing, pivotable body sides in the area of one of the V-shaped grooves to be cut based on the first step of the procedure;

FIG. 2 The board section according to FIG. 1, after the second step of the procedure;

FIG. 3 The board section according to FIGS. 1 and 2, after cutting of the V-shaped groove, the so-called miter groove;

FIG. 4 An enlarged view of the details at X in FIG. 3;

FIG. 5 A front view as in FIG. 3 of the body sides of a body folded from the initial board; and

FIG. 6 An enlarged view of the details at X in FIG. 5.

FIG. 1 shows in detail the section of an initial board 1 in the area of one of the miter grooves to be cut, of which as a rule three are provided in the board 1 in order to separate four body sides from one another that may be folded together to form an enclosed body possessing a square or rectangular cross-section. A finished body possesses an outer side formed from the lower side 2 of the board 1, and to which the board 1 is laminated with a veneer layer 3. This side hereafter designated as the outer side 2 of the board 1 opposes an inner side 4 that hereafter faces inward in the finished body. The inner side 4 of the board 1 may also be covered with a lamination, but this is not pertinent to this method.

A starter groove 5 is cut along a straight oblique line starting from the inner side 4 that reaches as far as the veneer layer 3 on the outer side 2 of the board 1. The starter groove 5 possesses a rectangular cross-section, and is cut perpendicular to the plane of the board 1. The starter groove 5 possesses a groove base of final width that corresponds to the width of the starter groove 5. The starter groove 5 is cut using a narrow router or a saw blade. In practice, it thus possesses a width on the order of 3 mm.

As FIG. 2 shows, a plastic material 6 is injected into the starter groove 5 in fluid form. Depending on the dimension of the injection nozzle through which the plastic material 6 is injected into the starter groove 5, a widening of the starter groove facing the upper inner side 4 of the board 1 may be provided that, independent of this, maintains a rectangular or square cross-section in its lower area above the groove base 15. Thus, in the illustrated embodiment example, the starter groove 5 according to FIG. 2 possesses oblique flanks 19 in its upper area. The injected plastic material 6 extends out from the veneer layer 3 that forms the groove base 15 over a partial height of the starter groove 5. If the starter groove 5, as FIG. 2 shows, widened as it goes up, the fill height of the plastic material 6 suitably covers the rectangular or square cross-section area of the starter groove 5. The fluid plastic material 6 hardens in the starter groove 5, but the plastic material remains elastic in its hardened state.

As FIG. 3 shows, a V-shaped groove 7 is cut as a miter groove symmetrically to the central plane of the starter groove 5 that extends oblique to the longitudinal dimension of the board and stands perpendicular to the board plane. The angle of the V-shaped groove 7 is 90°, and correspondingly the flanks 8 of the V-shaped groove 7 are perpendicular to each other. When the V-shaped groove 7 is cut, a portion of the plastic material 6 injected into the V-shaped groove 7 is removed. The entire contour of the starter groove 5 is cut away when the V-shaped groove 7 is cut since the starter groove 5 possesses a considerably smaller cross-section than the V-shaped groove 7. This also applies when, as FIG. 2 shows, the starter groove 5 is widened in its upper area.

As FIG. 4 shows, the V-shaped groove 7 is cut into the hardened plastic material 6 to the point that a spar 9 of plastic material 6 remains between the face of the V-shaped groove and the veneer layer 3. Since the width of the starter groove 5 at the groove base 15 (FIG. 1) is greater than the width of the V-shaped groove 7 in its face area, the plastic material 6 forms attachment spars 17 on both sides of the spar 9 after the V-shaped groove 7 is cut, by means of which a particularly good bond of the plastic material 6 is formed with the material of the initial board 1. The attachment spars 17 that extend along the V-shaped groove 7 on both sides may, so to speak, be viewed as hinge bands that in this case are of one piece with the spar 9. Overall, the plastic material 6 possesses a cross-section shaped somewhat like a dovetail after the V-shaped groove 7 is cut, whereby the V-shaped groove 7 may possess a flattening 16 in its face area.

By cutting the V-shaped groove 7, the miter groove, body sides 10 are separated from one another from the initial board 1 that are pivoted 90° with respect to one another by closing the V-shaped groove 7. For this, the spar 9 of the plastic material 6 forms a so-called film hinge that holds the body sides 10 together. The hardened plastic possesses adequate elasticity at least in the area of the spar 9. When the body sides 10 are folded or pivoted, either the veneer layer 3 is stretched over the outer edge 18 of the body (FIG. 5), or the veneer layer 3 breaks along this edge 18. For this, the veneer layer 3 may be weakened in that the veneer layer 3 is etched from the outer side 2 of the body sides 10, which is performed using the tool 11 shown in FIG. 3. A narrow cut line 12 thus results, as FIG. 4 shows.

FIGS. 5 and 6 show that, after folding the body sides 10, the plastic material 6 forming the film hinge along the outer body edges 18 faces inward, and is covered by the veneer layer 3. Formation of a clean miter joint 13 in whose area the flanks 8 of the V-shaped groove 7 rest one upon the other is not hindered by the plastic material 6 partially forming the groove flanks 8. The outer adjacent face edges of the two sections of the veneer layer 3 projecting above the edge may be cleaned along the outer body edges 18 by cutting or grinding a chamfer here. The important fact in this connection is that the veneer layer 3, or the sections of the veneer layer 3 extending to the body edges 18, are firmly bonded to the plastic material 6 so that particularly in the area of the spars 9 forming the film hinge, the veneer layers 3 are reinforced by the plastic material 6 along the bend or break line. The chamfers 14 may be created along a diagonal direction to each body edge 18 up to the plastic material 6, or into it, whereby the plastic material 6 is more or less visible in the area of the folded film-type spar 9. There is no danger of separation of the veneer layer 3 in the areas of the body edges 18 because of a solid bond between the end sections of the veneer layer 3 and the plastic material 6. This advantage also exists, of course, if the chamfer 14 is not created on the end sections of the veneer layer 3. 

1. Method to produce a furniture body with body sides (10) of wood or similar material joined together at common edges by means of miter faces, in which a V-shaped groove (7) is cut into a board (1) of wood or similar material that includes a veneer layer (3) of plastic or a veneer on the side of the finished body facing the outer side (2), from its inner side (4) along each of several straight lines in the area of the body corner edge to be formed to a depth meeting the veneer layer (3), after which the body sides (10) thus separated from one another are pivoted together by closing the V-shaped groove (7) forming the miter faces with their flanks (8) into which a plastic has been introduced, whereby the veneer layer (3) is deformed or broken along the edges thus formed, characterized in that before cutting the V-shaped groove (7), a starter groove (5) with smaller cross section is cut through to the veneer layer (3) at the same location that possesses a groove base (15) with a final width that extends to both sides over the face area of the V-shaped groove (7) to be produced subsequently, and that a fluid plastic material (6) is introduced into the starter groove (5) where it hardens and remains partially elastic at least near the areas of small cross section, filling the starter groove (5) at least partially from the veneer layer (3) and binding with the material of the board (1) and of the veneer layer (3), after which each V-shaped groove (7) is cut through the board material and through the hardened plastic material (6) so that an elastic, film-like spar (9) of the plastic material (6) remains between the face area of the V-shaped groove (5) and the veneer layer (3).
 2. Method as in claim 1, characterized in that the starter groove (5) is formed at least in the area of its groove base (15) with a rectangular or square cross-sectional shape to be symmetrical to the oblique plane perpendicular to the board plane through the line along which the V-shaped groove (7) will subsequently be cut.
 3. Method as in claim 1 or 2, characterized in that laminated plywood material is used as the board material.
 4. Method as in one of claims 1-3, characterized in that polyurethane plastic with thermoplastic properties is used as the plastic material (6).
 5. Method as in one of claims 1-4, characterized in that the plastic material (6) is injected into the starter groove (5) under pressure.
 6. Method as in one of claims 1-5, characterized in that the V-shaped groove (7) is cut with a flattening (16) in the face area, whereby the width of this flattening (16) is less than the width of the starter groove (5) at its groove base (15).
 7. Method as in one of claims 1-6, characterized in that the veneer layer (3) on the side opposite the V-shaped groove (7) is cut in or cut through along the face line of the V-shaped groove (7) before the body sides (10) are pivoted together.
 8. Method as in one of claims 1-7, characterized in that the cut or break lines of the veneer layer (3) are cut or ground along the body edges for the purpose of mounting a smooth chamfer (14) after the body sides (10) are pivoted together.
 9. Method as in claim 8, characterized in that the plastic material (6) is etched at the cut or break edge of the veneer layer (3) near the folded spar (9) when the chamfer (14) is cut. 